Make ipn.Options.Prefs a pointer.

This is a prelude to making it truly optional, once state
management has moved into the backend. For now though, it's
still required. This change is just isolating the bubbling-up
of the pointerification into other layers.

Signed-Off-By: David Anderson <dave@natulte.net>

cmd/tailscale/ipn.go

@@ -90,7 +90,7 @@ func main() {
 
 	bc := ipn.NewBackendClient(log.Printf, clientToServer)
 	opts := ipn.Options{
-		Prefs:     prefs,
+		Prefs:     &prefs,
 		ServerURL: *server,
 		Notify: func(n ipn.Notify) {
 			log.Printf("Notify: %v\n", n)

ipn/backend.go

@@ -53,7 +53,7 @@ type Notify struct {
 type Options struct {
 	FrontendLogID string // public logtail id used by frontend
 	ServerURL     string
-	Prefs         Prefs
+	Prefs         *Prefs
 	Notify        func(n Notify) `json:"-"`
 }
 

ipn/e2e_test.go

@@ -170,7 +170,7 @@ func newNode(t *testing.T, prefix string, https *httptest.Server) testNode {
 	n.Start(Options{
 		FrontendLogID: prefix + "-f",
 		ServerURL:     https.URL,
-		Prefs: Prefs{
+		Prefs: &Prefs{
 			RouteAll:         true,
 			AllowSingleHosts: true,
 			CorpDNS:          true,

ipn/fake.go

@@ -21,7 +21,7 @@ func (b *FakeBackend) Start(opts Options) error {
 		log.Fatalf("FakeBackend.Start: opts.Notify is nil\n")
 	}
 	b.notify = opts.Notify
-	b.notify(Notify{Prefs: &opts.Prefs})
+	b.notify(Notify{Prefs: opts.Prefs})
 	nl := NeedsLogin
 	b.notify(Notify{State: &nl})
 	return nil

ipn/handle.go

@@ -49,7 +49,9 @@ func (h *Handle) Start(opts Options) error {
 	h.netmapCache = nil
 	h.engineStatusCache = EngineStatus{}
 	h.stateCache = NoState
-	h.prefsCache = opts.Prefs
+	if opts.Prefs != nil {
+		h.prefsCache = *opts.Prefs
+	}
 	xopts := opts
 	xopts.Notify = h.notify
 	return h.b.Start(xopts)

ipn/local.go

@@ -53,7 +53,6 @@ type LocalBackend struct {
 }
 
 func NewLocalBackend(logf logger.Logf, logid string, e wgengine.Engine) (*LocalBackend, error) {
-
 	if e == nil {
 		panic("ipn.NewLocalBackend: wgengine must not be nil")
 	}
@@ -114,6 +113,10 @@ func (b *LocalBackend) SetCmpDiff(cmpDiff func(x, y interface{}) string) {
 }
 
 func (b *LocalBackend) Start(opts Options) error {
+	if opts.Prefs == nil {
+		panic("Prefs can't be nil yet")
+	}
+
 	if b.c != nil {
 		// TODO(apenwarr): avoid the need to reinit controlclient.
 		// This will trigger a full relogin/reconfigure cycle every
@@ -136,7 +139,9 @@ func (b *LocalBackend) Start(opts Options) error {
 	b.hiCache = hi
 	b.state = NoState
 	b.serverURL = opts.ServerURL
-	b.prefs = opts.Prefs
+	if opts.Prefs != nil {
+		b.prefs = *opts.Prefs
+	}
 	b.notify = opts.Notify
 	b.netMapCache = nil
 	b.mu.Unlock()

ipn/message_test.go

@@ -96,6 +96,7 @@ func TestClientServer(t *testing.T) {
 	ch := make(chan Notify, 256)
 	h, err := NewHandle(bc, clogf, Options{
 		ServerURL: "http://example.com/fake",
+		Prefs:     &Prefs{},
 		Notify: func(n Notify) {
 			ch <- n
 		},

ipn/prefs.go

@@ -103,7 +103,7 @@ func (uc *Prefs) Copy() *Prefs {
 	return &uc2
 }
 
-func LoadPrefs(filename string, enforceDefaults bool) Prefs {
+func LoadPrefs(filename string, enforceDefaults bool) *Prefs {
 	log.Printf("Loading prefs %v\n", filename)
 	data, err := ioutil.ReadFile(filename)
 	uc := NewPrefs()
@@ -136,7 +136,7 @@ post:
 		uc.WantRunning = true
 	}
 	log.Printf("Loaded prefs %v %v\n", filename, uc.Pretty())
-	return uc
+	return &uc
 }
 
 func SavePrefs(filename string, uc *Prefs) {